Hi,
I was asking about latching circuits.
I think it was someone else who offered the idea of a latching switch. I have not followed that up.
There was a thread recently about wiring switch on relays to give a latch on and auto latch off from a push to make switch. Its not current but ran about 5 or 6 weeks ago.

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regards Andrew T.
Sent from my desktop computer using a keyboard

Hi there...
Need to differentiate between <brown outs> and near <power outages>..both require different circuit analogies. Timing wise... most electronic gear has enough CV hold-up to accept brown outs, but a total loss i.e we all know what happens to computers.

If a brown out preceeds the power failure,i.e large AC volts dip the equipment volts may still hold up before undervoltage flag shows....Most dangerous is an intermittent supply failure which may suddenly reapply full AC supply. I get alot of this up here when thunderstorms are around. A fast 20ms breaker breaker can be annoying, but it isn't when a high VA transformer is connected.

The subject of under voltage; overvoltage; and other various protection is important to reliability.